Snap switch



1953 R. G. LE TOURNEAU 2,629,791

SNAP SWITCH Filed June 16, 1951 I9. 6". 6 TOMQA/'fid IN VEN TOR.

Patented Feb. 24, 1953 UNITED STATES PATENT OFFICE,

SNAP SWITCH.

Robert G. Le Tourneau, Long-View, Tex.

ApplicationJune 116, 1951, Serial Nm 231,939

1 Claim.

This invention relates to electrical switches and; more particularly to momentary contact switches used to limit the travel of some electrically operated device, and impart periodic or continuous motionto a motor.

The primary object of this invention is to provide a two-position switch which includes an adjustable leaf spring for making and breaking contact. therein.

Another'object-is to provide a leaf spring for a momentary contact switch which includes thereon contacts which impart a wiping action to their mating contacts under the action of the spring when making or breaking thecontacts.

A further object is to provide a leaf spring ineluding corrugations at its outer edges to permit rapid adjustment of the tension. therein with standard tools.

A still further object is to provide a plunger, for operating the leaf spring, which isthreaded to receive an external coil spring to prevent overtravel of the plunger with resultant damage to the switch.

Yet another object is to provide a two-position switch which is easily converted from a momentary contact switch to a positive acting switch.

These and other objects will be apparent from a perusual of the following specification and drawing, in which:

Figure 1 represents a top plan view of the assembled switch.

Figure. 2, represents a. sectional elevational view of the switch taken along the lines 2-2 of Figure 1.

Figure 3 represents an end view of the switch shown in Figure 1.

Figure 4 is a detail plan view of the leaf spring of this invention.

Figure 5 is a detail elevational viewof the spring of Figure 4.

Figure 6 is a detail elevational view of the plunger of this invention.

Figure 7 represents a modified plunger for use in installations where momentary contact is not desired.

Figure 8 represents a modified plunger for use in this switch. where an external spring is not required Referring now moreparticularly to the characters of reference, on the drawing, numeral i represents, the two-section housing of nonconducting material which encloses the operating mechanism of this switch. The two separating sections, Ia and lb of this housing are held togather by through, bolts i and nuts 3 which fit.

into their respective recesses 4 in the outer surface of the housing. The matching surfaces of these sections come together snugly in a plane represented by. the, line 5. in Figures 1 and? 3. Adjacent this line. at the top and bottom of the housing indentures 6 are formed to receive'removable terminals 1' and m for connecting electric leads to this switch. I'erminalsl at the top of the housing are connected to leads when it is desired to provide a normally off switch and bottom terminals lav are connected when it is desired toprovide a normally on switch as will be subsequently explained. Sections Ia and lb, comprised of relatively thin walls 8, combine to form an enclosed recess 9 in which the switch mechanism operates.

Plunger It. (also of insulating material): egtends centrally through opening I l. orupper. boss 2 at the top of housing I. andinto a, recess [3 of a lower boss M atrthe bottom of thehousing. Plunger Hi. includes a threaded section L5 which receives coil spring I Swhichsurrounds theupper neck I? of the plunger and acts as a. bufier to prevent damage to the switch or plunger due, to overtravel, of the actuating mechanism which trips-this limit switch. The lower end. [80f the plunger is drilled as at recess [9. to receive a smaller coil spring 29 to normally maintain, the plunger ina raised position. A square section. 2-! is formed on. the plunger nearits lower end, and a central section 2 2 just, above itextends upward to groove 23, which, together with groove 24 in boss l2; forms a means for-seating sealing boot 25.; which ispresent to prevent dirt or: grease from entering the interior of the switch. Square sectionE i. is slotted as at 21 on twooppositelsides to receive the free endsv 28 of arms. as on, leaf spring 38.

Plunger 58- is one modification. of plunger H3 wherein a rubber tip 55; includingan indenture 56 is secured to the top portion of neck Ha by means of a cementing'material 51. When this plunger is installed in housing I the spring 20 is not usedand the switch then becomes a "positive acting, two-position switch which is could be converted to either of the modified types 59 or 69 with a minimum of effort.

Leaf spring 30 may be stamped in one operation from a single strip of metal and includes cantilever type arms 29 which extend inwardly from either side but terminate short of the center. Outer strips 3| connect the end sections 32 and are corrugated by a special die. Silver contacts 34 and 35 are attached to end sections 32 on opposite sides. Contacts 34 are welded to the top side of the leaf spring 39 in a longitudinal direction and contacts 35 are welded to the underside of the spring in a transverse direction.

Terminals 1 and 1a include a central threaded section 49 to receive terminal screws 4| and Ma. The upper terminals 1 have a transverse contact 42 atthe underside thereof to engage upper longitudinal contacts 54 when the switch has been thrown. The lower terminals la include longitudinal contacts 43 which normally engage transverse contacts 35 of spring 39.

When assembled for operation, as represented in Figure 2, arms 29 engage slots 21 of plunger l9. It is to be noted that the distance between the slots 21 of the plunger I9 is wider than the space between the ends 29 of arms 29 in the plane of the leaf spring 39. This feature causes the arms 29 to be placed in compression and the outer strips 3! to be placed in tension and insures a positive over center snap in each direction of movement of the leaf Spring. The spring 29 engages recess l9 and forces the plunger [9 upwardly until the top side of square section 2| strikes the underside of boss l2. This action causes arms 29, being under compression, to exert a downward force and firmly engage contacts 35 with contacts 43. When plunger I9 is forced downwardly by an external pressure on spring l6 suflicient to overcome the upward pressure of spring 29, arms 29 pass below the plane of leaf spring 39 and the leaf spring is tripped and arms 29 then point upwardly from grooves 21 and apply an upward pressure and force contacts 34 into engagement with contacts 42. Since the matching contacts are positioned crosswise to each other, and since corrugated strips 3| expand lengthwise during the tripping action which takes place when arms 29 are moved, there results a wiping action between the contacts which prevents the accumulation of carbon thereon.

When electrical leads (not shown) are connected to the lower terminals 1a, spring 29 and leaf spring 39 cooperate to cause the contacts 35 and 43 to be engaged when the plunger is in its normal position. However, when spring [6 and plunger l9 are depressed sufficiently to snap the leaf spring and cause contacts 34 and 42 to be engaged, the switch is in its momentarily off position. As long as sufficient pressure is applied to the plunger to depress spring 29 the contacts 42 and 34 will remain engaged, and since there are no leads connected to terminal 1, the switch will not transmit any current. When the external pressure is released, spring 29 will return the plunger I 9 to its normally on position. If electrical leads are connected to the upper terminals 1 by means of terminal screws 4!, there will be no current transfer until the plunger l9 has been depressed and contacts 34 and 42 are momentarily engaged. When this connection is employed, the switch will be in its normally off" condition.

Spring I6 may be as long as desired, and it will be observed that an electrically actuated mechanism will be able to strike the spring I. and compress it sufliciently to cause plunger I 9 to move down and trip leaf spring 39 without ever touching plunger 19 directly, and of course, when the leaf spring 39 has separated contacts 35 and 43, the electric power to the actuated mechanism will be interrupted and no further travel on its part may take place.

In the modified embodiment employing plunger 59, leads may be connected to either terminals I or 1a since the switch will operate equally well in either direction when used as a positive acting switch. In another embodiment embodying the plunger 69, the switch may operate as normally on or normally off and the plunger must be held down manually for the intended operation as spring 29 will return it to its extended position when released. A sealing boot or bellows 25 is employed with each plunger to prevent entry of foreign matter around the plunger.

Adjustment of the leaf spring of this switch may be accomplished readily and accurately by employing a pair of pliers to compress the two sides 45 of a single corrugation hump such as 45 of corrugated strip 3|. By compressing a hump on each strip 31 the distance between end sections 32 will be shortened, and also the arms or stiff legs 29 will have their ends 28 moved closer together. When the arms 29 are installed on plunger 19, as they will be when ends 28 are placed in grooves 21, the tension in strip 3| will be greater than before and therefore the pressure required to push plunger l9 down will be increased. On the other hand, if the two sides 46 are separated the tension of strips 3| will be less when assembled and it will require less pressure to depress plunger I9. The use of contacts in transverse relation will permit considerable adjustment of spring 39 and even will allow for misalignment of the contacts.

From the foregoing description it will be readily seen that there has been produced such a device as substantially fulfills the objects of the invention as set forth herein.

While the specification sets forth in detail the present and preferred construction of this mechanism, still in practice such deviations from such detail may be resorted to as do not form a departure from the spirit of the invention as defined by the appended claim.

Having thus described the invention, the following is claimed as new and useful and upon which Letters Patent are desired:

A snap action switch comprising: an elongated hollow housing; an upper boss on said housing having a central opening therethrough; a lower boss on the housing having a recess therein; an actuating member slidably mounted in said opening and said recess; said housing being divided lon itudinally along a plane passing through the axis of said actuating member and into two substantially complementary sections; means extending transversely through said housing sections and tightly securing said housing sections together; a resilient diaphragm connecting said actuating member and said housing to form an airtight seal therebetween; a leaf spring in said housing comprising resiliently extensible outer strips, said outer strips being substantially sinusoidal in cross-section throughout the major portion of their length, opposed inner arms and end sections connecting said strips and arms; said actuating member having a portion disposed between the inner ends of said arms; said portion 5 6 having slots for receiving said inner ends for pivotal support thereof and being wider between REFERENCES CITED said inner ends than the space between said ends The following references are of record in the in the plane of the spring, whereby said inner me of this patent: arms are placed in compression and said outer 5 strips are placed in tension; movable contacts on UNITED STATES PATENTS said end sections; said housing sections having Number Name Date complementary recesses formed in the adjacent 1,198,340 Garretson Sept. 12, 1916 faces thereof and on either side of said actuat- 1,799,651 Siegmund 1 Apr. 7, 1931 ing member and substantially in alignment with 10 1,806,188 Adams May 19, 1931 said movable contacts; fixed contacts mounted in 1,907,931 Henderson May 9, 1933 said recesses; said movable contacts and said 1,907,932 Pugh May 9, 1933 fixed contacts disengaging with a wiping action 1,944,215 Burr 1 Jan. 23,1934 upon over-center movement of said leaf spring; 2,184,611 Cobbett Dec. 26, 1939 each of said contacts having a long dimension in 15 2,332,911 Hausler M Oct. 26, 19 13 one direction and a relatively short dimension in 2,396,332 McBerty Mar. 12, 19 16 a dimension 90 from said one dimension, each 2,476,056 Martin July 12, 1949 of said contacts carried by said end sections being 2,518,255 Roeser Aug. 8, 1950 disposed to contact its associated housing con- 2,526,850 Charbonneau Oct. 24, 1950 tact with its long dimension normal to the long 20 dimension of said associated contact; said actu- FOREIGN PATENTS ating member having a recess therein; and a coil Number Country Date spring mounted within the recess in said lower 553,665 Great Britain May 31, 19-13 boss and within the recess in said actuating 594,114 Great Britain Nov. 3, 1947 member for biasing said actuating member to non-actuating position.

ROBERT G. LE TOURNEAU. 

